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. 2025 Nov 24.
doi: 10.5435/JAAOS-D-25-00983. Online ahead of print.

Prognostic Role of BUN-to-Albumin Ratio, Albumin-to-ALP Ratio, and Mortality in Critically Ill Patients With Hip Fracture: Analysis of the MIMIC-IV Database, 2008 to 2019

Chih-Hui Chen  1 , Chiu-Liang Chen, Yi-An Li, Yu-Cheng Lo
Affiliations

Prognostic Role of BUN-to-Albumin Ratio, Albumin-to-ALP Ratio, and Mortality in Critically Ill Patients With Hip Fracture: Analysis of the MIMIC-IV Database, 2008 to 2019

Chih-Hui Chen et al. J Am Acad Orthop Surg. .

Abstract

Introduction: Hip fractures in critically ill patients are associated with high morbidity and mortality. Simple, accessible biomarkers that can predict outcomes are crucial for early risk stratification. This study aimed to evaluate the prognostic value of blood urea nitrogen-to-albumin (BUN/albumin) and albumin-to-alkaline phosphatase (albumin/ALP) ratios in predicting mortality in critically ill patients with hip fractures.

Methods: This retrospective cohort study included data (including BUN, albumin, and ALP values at admission) of adults with hip fracture admitted to the intensive care unit (ICU) extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Primary outcomes were 28-day and 1-year all-cause mortality. Multivariable logistic regression and Cox proportional hazards models were used to assess associations between BUN/albumin and albumin/ALP and 28-day and 1-year all-cause mortality. Receiver operating characteristic analysis was used to evaluate discrimination.

Results: In total, 265 patients with hip fractures were included. Higher BUN/albumin were independently associated with increased 1-year mortality (adjusted hazard ratio [aHR] = 1.39, 95% CI, 1.06 to 1.82, P = 0.018), with the highest tertile showing significantly greater risk (aHR = 2.67, 95% CI, 1.10 to 6.47, P = 0.030). A higher albumin/ALP was associated with reduced 1-year mortality (aHR = 0.13, 95% CI, 0.02 to 0.81, P = 0.029). Receiver operating characteristic analysis demonstrated only modest improvements in biomarker predictive performance.

Conclusion: BUN/albumin and albumin/ALP are independently associated with long-term mortality in critically ill patients with hip fractures and may serve as practical tools for early risk assessment.

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